Re: [PATCH 2/6] mm: kswapd: Keep kswapd awake for high-order allocations until a percentage of the node is balanced

On Thu, 09 Dec 2010, Mel Gorman wrote:

> When reclaiming for high-orders, kswapd is responsible for balancing a> node but it should not reclaim excessively. It avoids excessive reclaim by> considering if any zone in a node is balanced then the node is balanced. In> the cases where there are imbalanced zone sizes (e.g. ZONE_DMA with both> ZONE_DMA32 and ZONE_NORMAL), kswapd can go to sleep prematurely as just> one small zone was balanced.> > This alters the sleep logic of kswapd slightly. It counts the number of pages> that make up the balanced zones. If the total number of balanced pages is> more than a quarter of the zone, kswapd will go back to sleep. This should> keep a node balanced without reclaiming an excessive number of pages.> > Signed-off-by: Mel Gorman <mel@csn.ul.ie>